Electrode for gaseous discharge devices



June 2-2, 1948. s. c. MILLER 3 ELECTRODE FOR GASEOUS DISCHARGE DEVICES vFiled April 16, 1946' INVENT.0R. SamaelCY/llziller Patented June 22,1948 ems-1 amuel Miller, New Ydiii, I A ina-seat Mari-1 f6, 1946',sea-1N0. 662,421

8 cigars; (Cl. ire-26) This invention relates to gaseous electricaldischarge devices, more particularly to the electrode terminal endconstructilon ofsuch a tubinlar illuminant.

Known to me is the provision of me'ans'tasiip port a shell electrode atthe terminal end of a gaseous electrical di-schargedevice by inclusionof spacer material between theshll' electrodei'an'd the glass envelopein which the shell electrode is sealed. Such spacer supportsareoemployedto prevent the electrode fromj saggingafromits concentric axial positionin the envelope to where it contacts the glass envelope. Thisacti n ,mayoccur during processing of the gaseous electrical discharge deviceandresult ineithen cracking of a s or it p atio i- .Theusep s ers cannotbe controlled with any deg ree o f clg se q r n and a ru ia llsnmeeteffie 9: r d e d envelope ism m inta eabl v10? 1 om cia glass, ub ng r. thsfia slirer s size Within a wide ran'gel The commercialjorms of glasstubing employd'for making illilimin ts or electrical signs donot wantsiichlclos tion of size of tubing to doj xnore thiantojh roughapproximation between theshe and its" glass envelope; andthejiiitrp edsacer material. Thus, even if glass oi high heel anceis employed, itfiscommerc an tom'aintain close working dime the shell electrode andtheenvelo I have discovered that the g1 viceorilluminant need not b"glass'in forming the] envelo 'e' atflth v endjholdin'g theelectrode; I 7ma an eh epf ri i ceramic material known as'jAl this material'has'alinear co' effi expansion and compatibility to' t that the shellelectrode I may be sea contact withit, I' have r nner the ceramicmaterial anages; A U into a' size of such close tolerancethat velope forthe electrodg may bein cl w h, el ip mt. m i i e i venting theelectrical the putside of the electro a" ceramic envelope di ta ictthei'eetrbaeshar; u seamen as part o-f the; glass 116mg 1 tubularilluminant or displaying ceramic'maer ai, pereemei-iy'A1 in united by a?butt joint sealitdth'e heretaroreempioyedmmaking'tfies inhminents.

Accordingly, it is anobje'ct' of my invention to provide a gaseouselectrical discharge device in which the terminal end includesa' shellelectrode' and an envelope within which said electro'de nests,substantially in contact" therewith to hold the electrode againstsagging while pro-' tecting' its periphery and the lead-in wires fromthe electrical discharge which may accentuate sputtering or destroy anattack on the outside of the electrode and lead in wires.

It is further objct'of my inventidn' t o' p vide in a gaseous electricaldischarge device a erm na n cqns u c whi iin lu iashelelectrodejcomprising an envelope of afirainid material within which saidelectrodelnests eoncentrically and in contact; with the envelope withinclose tolerances of sizes v g V p Itis still further an object of, myinvention to provide; a gaseous electrical discharge gdevice in whichthe terminal end thereof includes a shell electrode sealed inoverthe'lead-in' wires or con diic'tor's' and in wjhichthe envelope isa'ceramic material with which the electrode is in Contac the envelopelikewise extending to form the en tire illuminant on display signwhereby" the translucent character of the ceramic material contributesto the illuminating value of the de vice. t is iurther. contemplated" byy inv rt;

tion' to provide an envelope forming a gaseous electrical dischargedevice wherein the Y electrode shell may be supported directly, incontactwith the envelope to minimize the attack on the out; side qj theshell and the lead-in wires for the electrode shell. M

Still further objects of his i vent n raided device in" which the bodyof the" illuminant a's the provision of" a gaseous electrical discharge"device in'which the employem'entof a ceramic material known asfAlsimageifec'ts s'iib'st'aiitial economies 'inass'embly and in' theconstruction "of these devices; I

To attain these objects and such further objects as may appear herein orbe hereinafter pointed out, I make reference to the accompanying drawingforming a part hereof in which- Figure 1 is a longitudinal sectionalview showing a composite glass and ceramic tubing for practising oneembodiment of my invention.

Figure 2 is a longitudinal sectional view with the electrode sealed inposition.

Figure 3 is a section taken on the line 3-3 of Figure 2.

Figure 4 is a section taken on the line 4--4 of Figure 2.

Figure 5 is a longitudinal fragmentary sectional View of anotherembodiment of my invention.

Making reference to the drawing, it is contemplated by me to provide anelectrode It for a gaseous electrical discharge device in which aterminal segment II is made of ceramic material.

The ceramic material which I have discovered to have desirableproperties is known under the trade name Alsimag No. 35, a product madeby the American Lava Corporation of Chattanooga, Tennessee, and iscomprised largely of alumina silica and magnesia. This material may beextruded or pressed into tubular sections and has a softeningtemperature of about 1430 degrees centigrade. In tubular sections whenthe walls are approximately .032 (thirty-two thousandths of an inch) thekilned material is almost translucent. The pressed material of almostnegligible water absorption properties is a desirable form to beemployed by me. This material in the form of a tube may have sealed toit a section of glass tubing 12 and I3 at opposite ends by butt jointseals I4 and i5 respectively. The glass tubing employed is that known tothe neon sign trade as lead-glass. The lead-glasses known as (3-1 andG12 supplied by the Corning Glass Works, have been used by mesuccessfully.

In making the butt joint seals I4 and I5, restraining the glass inabutting contact so that it does not extend over the sides of theceramic material, will minimize strains.

With a composite section thus provided, I may then insert the electrode16 in nested position within the ceramic section I I extending theleadin wires l7 towards the section I2 whereupon the section I2 is fusedand pressed to form the pedestal i8 and to form a seal for the lead-inwires I1. I may likewise position a ceramic collar shield i9 to protectthe rim 20 of the electrode shell 16. The ceramic collar [9 may be heldin this position by a spotting of fused glass or otherwise to hold thecollar in the rim overlapping position.

While I have shown and described the section H with an attached sectionl3 of glass at the butt joint seal IE, it will be understood that thesection 13 need not be affixed until after the terminal end comprisingthe ceramic section I! and the seal I8 have been completely formed.

It will also be understood that while I have described the section 13made of glass, it is contemplated by me that this section be acontinuation of the section II, and made of the same ceramic materialincluding luminescent or fluorescent ingredients added thereto duringthe plastic condition of the ceramic or as a coating which in the finaloperation of the gaseous electrical discharge device becomesselfexciting to be visible and produce the fluorescent eifects.

It is understood that where the tubing adjacent the terminal end is madeof ceramic material,

the walls of the tubing may be made so thin that the tubing ispractically translucent for all purposes.

In the embodiment illustrated in Figure 5, a terminal end 2| of thegaseous electrical discharge device is pressed or formed into agenerally cup-shaped segment having an integral bottom 22 formed with anaperture 23. An open mouth or rim 24 is provided at the opposite end.

As.before, an electrode shell it is chosen to fit snugly the interior ofthe ceramic terminal end 2| to nest therein in contact with the wallsthereof with the lead-in wires or conductors H, protruding through theorifice 23.

While in this position a glass bead is molten to form a seal 25 which ispressed in the aperture 23 to seal-in the lead-in wires ill. The rim 2%of the electrode l6 may be provided with a ceramic shielding collar 19as in the prior embodiment to fit inside the terminal ceramic end. Anassembly of this character may then be connected to a glass tube 26 byjoining the same to the terminal end 24 employing a butt seal 2%. Theassembly is then ready for completion of the illuminant or display signin the usual way.

It will be observed that by making a terminal end enveloping section atleast of the ceramic material, particularly Alsimag 35, that due to thehigh refractory nature of this material, its imperviousness and lowco-efiicient of expansion, direct contact between the electrode shelland the ceramic housing may be maintained during processing and theincident heat generated. By employing a pressed ceramic material closetolerances in sizes are possible and a fit between the shell electrodeand the ceramic collar not possible with the usual drawn commercialglass, may be secured. The high heat insulating properties of theceramic material eliminates the need for the cost and labor of applyingspacer materials such as mica, previously employed with electrodeassemblies of this kind. By close contact between the shell electrodeand the ceramic casing or envelope, the lead-in wires are protected fromattack by the electrical discharge during processing and operation. Theoutside surface of the shell electrode is likewise free from attack,thereby minimizing the darkening influence of the illuminant especiallywhere fluorescent coatings are carried by the tube.

It will be understood that while the sections 13 and 25 may be of glassof tubular contour, the electrical discharge device may be part of adevice in which the illuminant takes on a special contour, as theceramic material is susceptible of being extruded or molded into hollowblock letters during plastic cold working and may be then matured to itsfinal refractory properties in the kiln or furnace. The letters may bejoined by short lengths of glass tubing with the end members providedwith the terminal electrode assemblies.

The employment of a ceramic envelope about the shell electrode permitsof higher processing temperatures and therefore longer life to theilluminant assemblies. In general, it will be observed that a compactand efficient electrode terminal end has been provided, since the usualenlargement at this portion is not required. The density of the ceramicterminal fits in with ornamental efiects especially where it carriesfluorescent materials which minimizes the darkening effect of theelectrode, at this point.

Having thus described my invention and illustrated its use, what I claimas new and desire to secure by Letters Patent is:

1. In a gaseous electrical discharge device for forming part of aluminous tube the terminal end whereof includes a shell electrode sealedin over the lead-in conductors, the combination therewith of an envelopein gas sealing position within which said electrode nests concentricallyand substantially in contact therewith to hold the same against sagging,said envelope comprising a moldshaped ceramic tubular element.

2. In a gaseous electrical discharge device for forming part of aluminous tube the terminal end whereof includes a shell electrode sealedin over the lead-in conductors, the combination therewith of an envelopewithin which said electrode nests concentrically :and substantially incontact therewith to hold the same against sagging, said envelopecomprising a mold-shaped ceramic tubular element, the rim of which issealed in butt joint engagement with the luminous tube assembly.

3. In a gaseous electrical discharge device for forming part of aluminous tube the terminal end whereof includes a shell electrode sealedin over the lead-in conductors, the combination therewith of an envelopein gas sealing position within which said electrode nests concentricallyand substantially in contact therewith to hold the same against sagging,said envelope comprising a mold-shaped ceramic tubular element and aceramic shielding collar within said envelope and overlying the rim ofsaid electrode.

4. In a gaseous electrical discharge device the terminal end whereofincludes a shell electrode sealed-in over the lead-in conductors saidelec trode being directly in contact and supported by an envelopecomprising a ceramic tubular member, said member being sealed-in buttjoint contact with the luminous tube of the discharge dev1ce.

5. In a gaseous electrical discharge device the terminal end whereofincludes a shell electrode sealed-in over the lead-in conductors saidelectrode being directly in contact and supported by an envelopecomprising a ceramic tubular memher, said member being sealed in buttjoint contact with the luminous tube of the discharge device said tubecarrying a luminescent visible light excitable coating.

6. In a gaseous electrical discharge device the terminal end whereofincludes a section of a refractory ceramic impervious tubing, acoaxial-1y disposed electrode shell, having lead-in conductors sealed byglass at one end and a section of glass tubing in butt joint sealingcontact at the other end.

SAMUEL C. MILLER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,120,480 Baker June 14, 19382,310,980 Miller Feb. 16, 1943

